A tire for a heavy vehicle of civil engineering type, intended to be fitted onto a rim, is provided. The nominal diameter of the tire is at least equal to 25 inches. The tire comprises a tread having a radial thickness HT at least equal to 30 mm. The tread has a composition based on at least one diene elastomer, a reinforcing filler predominantly comprising a filler at least partially covered with silica, an agent for coupling the filler to the at least one diene elastomer and a crosslinking system. The dispersion of the filler in the elastomeric matrix has a Z score of greater than or equal to 70.